PX4 User Guide

# Freefly Systems RTK GPS

The Freefly Systems RTK GPS Module is a multiband RTK GPS module from Freefly Systems that provides highly reliable navigation. The modules can act as either rovers (when installed on an aircraft) or base stations (when plugged into a computer).

Main features include:

  • Multiband (L1/L2) receiver (Ublox ZED-F9P)
  • Concurrent reception of all 4 GNSS (GPS, Galileo, GLONASS, BeiDou)
  • Built-in magnetometer (IST8310), baro (BMP388), RGB LED, safety switch and safety LED

Note This module can be used with PX4 v1.9 or above (support for the UBlox ZED-F9P was added in PX4 v1.9).

FreeFly GPS Module

# Purchase

# Kit Contents

An RTK GPS kit includes:

  • 2x GPS modules with antennas
  • 3m USB C to A cable
  • Magnetic quick-mount for base station module (1/4-20 thread for tripod mounting)
  • Screws to mount onto a Freefly AltaX

# Configuration

RTK setup and use on PX4 via QGroundControl is largely plug and play (see RTK GPS for more information).

For the aircraft, you should set the parameter SER_GPS1_BAUD to 115200 8N1 to ensure that PX4 configures the correct baudrate.

# Wiring and Connections

The Freefly RTK GPS comes with an 8 pin JST-GH connector that can be plugged into a PixHawk autopilot. For use as a base station, the module has a USB-C connector

# Pinout

The Freefly GPS pinout is provided below. For some autopilots, like the Hex Cube and PixRacer, all that is needed is a 1-1 8-pin JST-GH cable.

Pin Freefly GPS
1 VCC_5V
2 GPS_RX
3 GPS_TX
4 I2C_SCL
5 I2C_SDA
6 BUTTON
7 BUTTON_LED
8 GND

# Specification

  • Ublox ZED-F9P GPS Receiver
    • Ultracap backup power for fast (hot-start) restarts
    • EMI shield over receiver for improved EMI immunity
  • IST8310 Magnetometer
  • Safety-switch and safety LED
  • RGB LEDs for status indication
    • NCP5623CMUTBG I2C Driver
  • BMP388 Baro on I2C bus
  • External, active antenna (Maxtena M7HCT)
    • SMA connector
  • STM32 MCU for future CAN-based communication
    • FW updates through USB connector
  • Connectivity:
    • USB-C
    • 2-way USB Switch to MCU and F9P
    • SMA for active antenna (20mA max)
    • 4-pin JST-GH CAN Bus (dronecode compliant)
    • 8-pin JST-GH UART/I2C -** Power:
    • Input from either (diode OR'd):
    • USB (5V)
    • CAN (4.7 to 25.2V)
    • (4.7 to 25.2V)
    • Power consumption <1W

# More Information

More information can be found on Freefly's Wiki